The long-term of this project is to reduce sexually transmitted diseases (STD) and their consequences in a group of at-risk adolescents. Our shorter term goals are to extend our observations about adolescents' sexual experiences as they relate to risk for recurrent STD and test behavioral interventions to reduce STD by decreasing behaviors that place the adolescent at risk for acquiring STD. The research is guided by The Health Belief Model of Compliance into which we have incorporated the theoretical underpinnings of the Theory of Reasoned Action and Conceptual Systems Theory. A prospective, longitudinal study of behavioral and psychosocial aspects of STD will be conducted among 600 adolescent females 15-19 years old of varied socioeconomic and ethnic backgrounds attending STD and adolescent clinics. Chlamydia trachomatis (Ct) will serve as the model STD. Using a randomized controlled design we will test the efficacy of three intervention models that vary the number of visits and the format of delivery (nurse/educator alone vs. computer assisted). Participants will be supported in adopting assertive health behaviors. This intervention will seek to: 1) increase compliance with medical treatment; 2)reduce the potential for developing long-term sequelae by supporting adolescent- initiated periodic screening of patient for Ct; 3) encourage early evaluation and treatment of symptoms; and 4) support the use of condoms to decrease the rate of second infections. Serial microbiologic cultures, the use of standard measures of psychosocial functioning, frequent detailed personal interviews and diaries will help determine the factors associated with compliance. This study will clarify the level of intensity and format of clinical encounter most effective in enhancing adolescents behavioral change.